Mabey, U.S. Pat. No. 7,744,693 B2 (Jun. 29, 2010), discloses lightweight composite materials and methods. Disclosed therein is a lightweight “mineral foam” composite, based on a reaction between mono-ammonium phosphate (MAP) and heavily burned, thus very low reactivity, magnesium oxide (MgO). The magnesium phosphate cement (MOP cement) product—which can contain a burnt coal residue such as fly ash, a low cost material—is effective as an insulating building material in blocks or panels; but, although it is fire-resistant, lacks a really high level of fire resistance and thus, while resistant to elevated temperatures, may not pass a North American Building Code mandated fire test such as the ASTM E-119 or ULC CAN4-S101 fire tests of building construction and materials, or the CAN/ULC-S124 test for thermal barrier fire protection of foamed plastic in a cost-effective manner.
Various other cementitious compositions are known, and desired for application in building construction. See, e.g., British Patent No. 5022 (Oct. 11, 1824) to Aspdin for artificial stone; U.S. Pat. No. 1,059,661 (Apr. 22, 1913) to Edison for manufacture of Portland cement; U.S. Pat. No. 3,226,240 (Dec. 28, 1965) to Crowley for a calcium aluminate cement composition; U.S. Pat. No. 4,352,694 (Oct. 5, 1982) to Smith-Johannsen et al. for a process of producing Sorel cement; U.S. Pat. No. 5,110,361 (May 5, 1992) to Alley et al. for magnesium oxychloride cement compositions and methods for manufacture and use; Caine et al., U.S. Pat. No. 7,658,795 B2 (Feb. 9, 2010) for magnesium oxychloride cement; and U.S. Pat. No. 8,066,812 B2 (Nov. 29, 2011) to Wu et al. for durable magnesium oxychloride cement and process thereof. Indeed, in Wu et al., in order to reduce the impact of carbonation on the long-term strength of a magnesium oxychloride cement (MOC cement) complex, included is an exfoliated vermiculite in a Sorel cement mix such as that disclosed in the patents mentioned above to Smith-Johannsen et al., which teaches the addition of phosphoric acid or its soluble salts as a means of improving the water resistance of a MOC cement, and to Alley et al., which teaches the addition of hydrochloric acid in order to make a MOC cement that is a durable concrete repair material. Such cementitious compositions, among other things, may have value in retarding the spread of fire in commercial or residential construction.
It is known, too, that certain cementitious compositions can be combined with metallic elements for reinforcement, support, and so forth. For example, ferrous reinforcing rod and mesh are well known adjuncts to various cementitious compositions such as Portland cement based concrete. Other metallic elements may include metal C-studs embedded in a mineral foam matrix such as disclosed by the aforementioned patent to Mabey.
The Mabey patent also discloses embedding a wooden stud in a mineral foam matrix.
Further enhancements perhaps may be made by the addition fibrous materials, such as man-made fibers, flax or hemp fibers and fines, oat husks and rice hulls. These may serve to ‘bulk up” a wet slurry without adding significant weight and/or improve the bending strength, flexural strength and compressive strength of the dried and cured composite matrix.
As good as they are, such cementitious materials and their combinations, to include those employing metallic adjuncts, are not without drawbacks. Among these, in certain cases, is a propensity to corrode metallic elements placed in contact with the set cement; in others is a lack of fire resistance; and in other cases is a loss of strength with long term exposure to moisture such as may be the case with MOC cement and magnesium oxysulfate cement (MOS cement). See, e.g., Qiao et al., “The application review of magnesium oxychloride cement,” J. Chem. Pharm. Res., 2014, 6(5):180-185.
While the foregoing improvements are obviously beneficial, it would be desirable to provide a composition having a reduced weight or density and/or having further improved fire resistance compared to such known products, to include not only the MOP cement product of Mabey but also MOC cement and other cements, to include MOS cement, to include as mentioned above. It would be desirable to provide a lightweight, structural assembly having a very high level of fire-resistance, and provide a construction material with improved functional properties. In general, it would be desirable to ameliorate if not eliminate one or more of such drawbacks and others known in the art. It would be desirable to provide the art an alternative.